Sentinel's Grimoire (鉄壁のグリモア, Teppeki no Gurimoa?, lit. Grimoire of Impregnability) is a recurring ability in the series. It is an ability used exclusively by Tyro. In the tutorial section of Final Fantasy Record Keeper regarding Soul Breaks Sentinel's Grimoire is called "Bulwark Grimoire".
Variations of Sentinel's Grimoire are used by Dr. Mog and Elarra as Roaming Warriors in certain dungeons. Both provide the same benefit, but Dr. Mog's Tactician's Grimoire has a duration of 26 seconds while Elarra's Fabula Guardian has a duration of 30 seconds.
grimoire is a textbook of magic. Such books typically include instructions on how to create magical objects like talismans and amulets, how to perform magical spells, charms and divination and also how to summon or invoke supernatural entities such as angels, spirits, and demons.A